HIV/AIDS is a significant health concern in Rwanda, particularly in urban centers like Kigali. Antiretroviral treatment (ART) adherence programmes are essential for managing HIV effectively and preventing drug resistance. A mixed-methods approach was employed, including quantitative data analysis from treatment records and qualitative interviews with healthcare providers and patients to gather insights into programme implementation and efficacy. Adherence rates improved by 15% over the three-year period, though there were significant variations in adherence across different ART regimens (p < 0.05). The ART adherence programmes have shown promising results but require targeted interventions to enhance overall adherence and optimise resource allocation. Further research should focus on improving medication supply logistics and patient education strategies, particularly in high-risk groups such as young adults and those with lower socioeconomic status. HIV/AIDS, Antiretroviral Treatment Adherence, Kigali, Rwanda, Programme Evaluation Treatment effect was estimated with $\text{logit}(p_i)=\beta_0+\beta^\top X_i$, and uncertainty reported using confidence-interval based inference.